[Feature Request]: Consolidate Tariffs to support Meters and EaaS alike

### Preflight Checklist

- [x] I have read the [Contributing Guidelines](https://github.com/EnAccess/micropowermanager/blob/main/CONTRIBUTING.md) for this project, if it exists.
- [x] I agree to follow the [Code of Conduct](https://github.com/EnAccess/micropowermanager/blob/main/CODE_OF_CONDUCT.md) that this project adheres to.
- [x] I have searched the [issue tracker](https://github.com/EnAccess/micropowermanager/issues) for a feature request that matches the one I want to file, without success.

### Problem Description

Currently, Tariffs are tightly coupled to Meters. However, in Energy-as-a-Service use cases similar concepts are deployed as customers pay "per day" or "per kwh".
Similar, to Meter Tariffs users of EaaS may wish to define a Tariff once, and then use it for multiple customers.

This is a follow up to: https://github.com/EnAccess/micropowermanager/pull/1403

### Proposed Solution

Expand the Tariff abstraction to allow Tariffs to be Meter as well as EaaS or others.

Also, adapt changes added in: https://github.com/EnAccess/micropowermanager/pull/1403

### Alternatives Considered

N/A

### Additional Information

_No response_